1. Field of the Invention
The present invention relates to a production method of a fluid dynamic-pressure bearing and a spindle motor furnished with the fluid dynamic-pressure bearing.
2. Description of the Related Art
Conventionally, various types of bearings are adopted in spindle motors used in hard disk drives. Such bearings include a fluid dynamic-pressure bearing, for example. The fluid dynamic-pressure bearing is provided with a shaft fixed to a rotor hub, a sleeve which is fixed to a base and into which the shaft is inserted, and a lubricating fluid retained between the shaft and the sleeve. In the fluid dynamic-pressure bearing, the rotor hub is supported in a condition where the rotor hub is not in contact with the sleeve (see, for example, Japanese Laid-Open Patent Publication No. 2003-088042).
In recent years, the density and the accuracy of hard disk drives are increased. In conjunction with the increase, the spindle motor used in the hard disk drive is required to rotate a rotor section having a rotor hub with high accuracy.
In order to rotate the rotor section with high accuracy, it is necessary that the accuracy of the rotor section be high. For the purpose of increasing the accuracy of the rotor section, it is necessary to perform various inspections not only after the completion of assembling the spindle motor but also in the middle of the assembling process thereof.
In the case where a spindle motor whose assembly is completed is determined not to satisfy the standards by the inspections, the spindle motor should be discarded. The discarding of spindle motor necessitates the cost. In addition, the discarding of motor deteriorates the productivity. Accordingly, it is preferred that some inspections should be performed before the completion of assembling the spindle motor and in a condition where only a small number of components for constituting the motor are mounted on the motor.
Moreover, in the inspections for the rotor section, in the case where an inspection gauge comes into contact with the rotor section, the press of the inspection gauge against the rotor section may disadvantageously cause the contact of the rotor section with the sleeve. As a result, at least one of the rotor section and the sleeve is damaged. Some of the bearings furnished with such a damaged rotor section or sleeve cannot exhibit desired performances as dynamic-pressure bearings.